Flame arrester



Aug. 17, 1948. R. c. HALL. 2,447,120

FLAME I ARRESTER Filed NOV. 10, 1943 3 Sheets-Sheet l lllll/lll/ 11,/111/ l1 f f f gy R/c'HA/zo CHA LL -HnRRis, KIECH, FOSTER Hmm/5 *met FOBTHE FIRM Aug. 17, 1948. R. c. HALL FLAME ARRESTER 3 Sheets-Sheet 2 FiledNov. l0, 1943 /NvEAv/ro/z R/CHARD C. HALL FOR THE FIRM HTroR/veys Aug1948. R. c. HAL.. 2,447,120

FLAME ARRESTER Filed Nov. l0, 1943 3 Sheets-Sheet 3 [NVE/wok HW HnRR/sF02. THE FIRM HTTORNEYS Patented Aug. i7, 1948 FLAME ARRESTR Richard C.Hall, Alhambra, Calif., assigner to Petroleum Essentials, Incorporated,Glendora, Caiif., a corporation of California Application November 1I),1943, Serial No. 509,813

1I) Claims. l

My invention relates to flame arresters, that is, devices which are usedto lower the temperature of the products of combustion far enough tostop the propagation of flame in the system. In many industries, it isnecessary to remove gases from combustion Zones while they are still ata temperature above that necessary to main-- tain flame temperature, andit is highly desirable in many such instances to cool these gases wellbelow ame temperature before discharging them into the air or intoconduits where ames might be injurious.

It is also sometimes desirable to deliver combustible gas mixtures intospaces in which they are burned, and it is necessary to prevent themfrom burning until they reach this space, which can be accomplished if aflame arrester is installed at the inlet to this space. It is also wiseto install such flame arresters at the outlet of any space through whichcombustible gas mixtures pass if combustion or explosion in such spacemust be prevented so that combustionoutside said space will not betransmitted to that space.

An object of my invention is to provide a flame arrester in which thecooling Velements are in the form of circular metal plates, and afurther object is to provide such an arrester in which the plates can bereadily removed for cleaning. During the operation of a flame arrester,particles of scot or carbon may accumulate on the plates, and it isnecessary from time to time to remove them and clean off the accumulatedcarbon, tar, and other foreign material.

In my flame arrester, I use plates in the form of circular metal discswhich are spaced apart by dimples to provide Iiuid passageways betweenthe plates, and these passageways are very likely to become clogged incontinued use by the tar or carbon. I have devised means by which thesediscs can be readily removed from the flame a1- rester for cleaningwhenever this is necessary.

A further object of the invention is to provide a flame arrester throughwhich the hot or cold gases are normally passed, and in which the platesor ame arrester elements may be removed without disconnecting the flamearrester from the conduit carrying the hot or cold gases, and still beable to keep these gases sealed in the system. The danger ofasphyxiation is eliminated when opening the arrester to remove theplates. In practice, it is desirable to use two of these arresters inparallel so that one may be cleaned while the other is in operationwhen-continuous operation is essential.

this arrester shell having a closed end 32.

Further objects and advantages will be made evident hereinafter.

In the drawings,

Fig. 1 is a section through the center of the device on a bent planeindicated by the line I--l of Fig. 2.

Fig. 2 is a section on a plane represented by the line 2-2 of Fig. 1.

Fig'. 3 is an elevation of one end of the arrester.

Fig. 4 is an elevation of the other end of the arrester.

Fig. 5 is an isometric View of the plug valve control mechanism.

Fig. 6 is a section on an enlarged scale through one of the plates on aplane represented by the line 6-6' of Fig. 2.

In the form of my invention illustrated in the drawings, I provide acasing I I which is provided with fins I2 to better enable 'it toradiate heat. This casing has a conical valve chamber I3 formed thereinand is provided with a primary cover I4 and a secondary cover I5. Theprimary cover I4 needs to be removed only at long intervals, and it is'suflicient if it is secured to the casing II by bolts IIS. Thesecondary cover I5 must be removed at frequent intervals for the purposeof cleaning the soot and 'tar out of the arrester, and it is secured bymore easily operated hand-wheels I'I turning on pivoted bolts I8.Fitting inside the conical valve chamber I3 is a valve body 2| which hasa conical outer surface 'and a concentric cylindrical arrester chamber22 formed therein. The casing Il has a casing inlet opening 23 and acasing outlet opening 24, and the valve body 2| has a valve inletopening 25 Aand a valve outlet opening 26. The opening 2E is so placedthat it communicates with the opening 24, and the opening 25communicates with the opening 23 lwhen the arrester is in the openposition shown in Figs. 1 and 2. The extent of these openingscircumferentially of the conical valve chamber I 3 is such that if the'valve body 2l is turned through an angle of from the position shown inFig. 2, the openings 23 and 24 are closed, and there can be no passageof gas into the arrester.

A pin 21 is fixed in the valve body 2I and slides in a slot 28 in thecover I4, which slot is of sufficient length to allow this movement oi90 to be made, stopping the rotation of the valve body 2| either in theopen or in the closed 'position. The pin 21 is carried by the closed'end 29 of the valve body 2l. In the cylindrical opening in the valvebody 2I I place an arrester shell SI, A

other, leaving arrester slots therebetween. Thesey indentations 36 arepreferably spherical, or symmetrical about the axis a-a, as shown inFig. 6. They are so spaced, as shown in Fig. 2, that the indentations onone disc 35 do not coincide in position with those on an adjacent disc.The object of this is not only to space the discs 35 apart apredetermined distance, thus insuring small and definite passagewaystherebetween, but also to force the gases to pass in tortuous pathsthrough the passageways with considerable turbulence, which assists incooling any flame that may attempt to pass through the arrester.

Threaded in the end 32 of the arrester shell 3| is a bolt 4|, andsecured to the outer end of the bolt 4| is a spacer and handle 42. Thebolt 4! projects upwardly through cylindrical holes in the centers ofthe discs 35 and is provided on its upper end with a nut 43. A similarbolt 44 projects downwardly from the cover 33 and also has a nut 45thereon. A loose sleeve 46 surrounds these nuts and is engaged therebyas the discs are separated.

When it is desired to clean the discs, the secondary cover l is removedby loosening the handwheels |I on the bolts I8, and, the spacer 42 beingused as a handle, the arrester shell 3| containing the discs may bedrawn downwardly as shown in Fig. l from the interior of the arrester.The discs can then separate due to the lost motion between the nut 43and the sleeve 46, and the accumulation of tar and carbon there- .l

on can be cleaned off. The spacer 42 is of sufficient length to insurethe arrester shell 3| aligning properly with the holes 23 and 24 so thatwhen the arrester is in open position, gases passing therethrough willpass through the arrester slots between the discs.

In practice, it is preferable to use two of these arresters in multipleso that when one is shut down the other may still be used withoutinterrupting the passage of gas from its source. When it is desired toclean the arrester. the valve body 2| is turned through an angle of 90from the position shown in Fig. 2 so that the interior of the valve bodyis isolated, the openings 23 and 24 being closed by the wall of thevalve body. For the purpose of turning the valve body, I provide a shaft5| which projects through a stuffing box 52, and which carries anindicator pointer 53, this indicator pointer indicating the open orclosed position, as shown in Fig. 3. It is desirable that the valve body2| be rmly seated in the conical opening in the casing and for thispurpose I provide means for pressing downwardly, as shown in Fig. 1, onthe outer end of the shaft 5|, thus forcing the valve body downwardlyinto tight contact with the conical opening in the casing. When thevalve body is so pressed tightly down, it is almost impossible to turnit, and it is necessary to pull upwardly on the shaft 5|, rlrstloosening the valve body from the casing llbefore an attempt is made torotate the valve body. For the purpose of providing a convenient meansfor both seating the valve body and rotating it, I provide the mechanismshown in Fig. 1 and isometrically in Fig. 5. This mechanism consists 4of bearing 6| rigidly supported on a plate which carries the pointer 53.Turning in the bearings 6| is a handle pivot 62 which has a central slot63 into which a fulcrum nut 64 projects, this fulcrum nut being threadedand rigidly secured to the shaft 5|, as shown in Fig. 1. A handle 65 isprovided on the handle pivot 62, and an eccentric pin 66 projectsthrough the handle pivot and the fulcrum nut 64 which has a slottherein, as shown in Fig. 1. When the handle is turned from the position61 to the position 68, it lifts the valve body 2|, as viewed in Figs. land 5, thus releasing it from intimate contact with the conical openingin the casing The valve body will then turn freely, and the handle canbe turned from the position 68 to a position 69. In the positions 61 and68, the pointer 53 indicates that the valve is open, and when the handleis turned to the position 69, the valve is in closed position. It isusual to then move the handle back into the vertical position, as shownin Fig. 5, toinsure tight contact with the walls and so that the valvewill be tightly closed. With the valve handle 65 in the position 61, itis impossible to secure sufficient leverage to turn the valve body 2|when in contact with the casing thus preventing the body 2| or casingfrom becoming scored or marked and making hardened surfaces unnecessary.

The method of operation of my invention is as follows. With the parts inthe positions shown in full lines in the drawings, hot gases passupwardly through the openings 23 and 25 into the interior of thearrester chamber and pass through the arrester slots between the plates.These plates tend to cool the gasesso that when they emerge from thearrester slots and pass through the openings 26 and 24 they aresufficiently cool that flame propagation will not continue. The arresteris operated in this manner, the gases being cooled by passingtherethrough, and also any large particles of carbon being arrestedthereby, until the operator notes that the ilow of gas through thearrester is somewhat impeded by soot and tar on the plates, whereupon hemoves the handle from the position shown at 61 to the position shown at68, turn-s the arrester from the open to the closed position by turningthe handle to the position 69, and then raises the handle back to theposition 67. This operation rst frees the valve from the conical innersurface of the casing in the movement of the handle from the position 67to the position 68. The valve is turned in the movement of the handlefrom the position 68 to the position 69, and the valve is again firmlyseated by moving the handle up to the position 67. The valve has thenbeen turned from the position shown in Fig. 2, and the openings 23 and24 are closed and sealed. The interior of the arrester is thereforetaken out of the gas flow. The operator then loosens the hand-wheels I1,takes olf the secondary cover l5, pulls the arrester shell 3| out of thevalve body, and the discs are in a position where they can be readilycleaned. If the system can be operated for short intervals without thearrester element, the operation can be accomplished in a few seconds andthe arrester placed back in service without the element while beingcleaned. The discs are cleaned, and the arrester shell is forced backinto the valve body; the cover is replaced, and the hand-wheelstightened, so that the discs are in the positions shown in Fig. l. Theoperator then turns the handle from the position 61 to the position 69,which loosens the valve body from its seat, turns it from the closed toopen position by moving the handle from the position S9 to the position68, and again tightens the valve in its seat by raising the handle fnomthe position 68 to the position Bl'. This operation can be very quicklyperformed without shutting down the flow of gas, which continuesthrough-the companion arrester. It may be done by unskilled laborWithout the use of tools, and a complete cleaning loi" the arrestertakes only a very short time.

I claim as my invention:

1. In a flame arrester, the combination of: a casing having a valvechamber therein which is concentric about an axis, said casing havingside casing openings through which gas can pass through said chamber ina direction substantially at right angles to said axis, and a bottomcasing opening; a valve body tting in said valve chamber and rotatableabout said axis and having an arrester chamber formed therein which hasan` inner wall concentric about said axis, said body having side valveopenings that register with the side ca-sing openings when the Valvebody is in open position, said side openings in said casing beingclosed, or blocked, by the walls of said valve body when said valve bodyis in its closed position, said valve body having a bottom valve bodyopening; an arrester shell adapted to iill and turn freely in said valvebody and having side openings coinciding with the side openings in saidvalve body, said arrester shell being of .such size that it may bereadily withdrawn through said bottom casing opening, and having a discchamber concentric about a disc axis formed therein; a series of discsso mounted in said disc chamber that there is a narrow slot or openingbetween adjacent discs, each disc being concentric about said disc axis;a bottom cover closing said bottom casing opening; and means outsidesaid casing by which the valve body can be rotated.

2. In a flame arrester, the combination of: a casing having a valvechamber therein which is concentric about an axis, said casing havingside casing openings through which gas can pass through said chamber ina direction substantially at right angles to said axis, and a bottomcasing opening; a valve body tting in said valve chamber and rotatableabout said axis and having an arrester chamber formed therein which hasan inner wall concentric about said axis, said body havingl side valveopenings that regi-ster with the side casing openings when the valvebody is in open position, said side openings in said casing beingclosed, or blocked, by the walls of said valve body when said valve bodyis in its closed position, said valve body having a bottom valve bodyopening; an arrester shell adapted to ll and turn freely in said valvebody and having side openings coinciding with the side openings in saidvalve` body, said arr-ester shell being of such size that it be readilywithdrawn through said bottom casing opening, and having a disc chamberconcentric about a disc axis formed therein; a series of discs somounted in said disc chamber that there is a narrow slot or openingbetween adjacent discs, each disc being concentric about said disc axis;a bottom cover closing said bottom casing opening; an operating shaftsecured to the upper portion of said valve body and projecting throughthe top of said casing; and means outside said casing by which -saidshaft may be turned.

3. In a flame arrester, the combination of: a casing having a valvechamber therein which is conical about an axis, said casing having sidecasing openings'through which' gas can pass through said chamber in adirection substantially at right angles to said axis, and a bottomcasing opening; a valvei body tting in said valve chamber and rotatableabout said axis and having an arrester chamber formed therein which hasan inner wall concentric about sai-d axis, said body having side valveopenings that register with the side casing openings when the valve bodyis in open position, said side openings in said casing being closed, orblocked, by the walls of said valve body when said valve body is in itsclosed position, said valve body having a bottom valve body opening;anarrester'shell adapted to fill and .turn freely in 'said valve? bodyand having side openings coinciding with the side openings in said valvebody, said arrester shell being of such size that. it may be readilywithdrawn through said bottom casing opening, and having a disc chamber.concentric about'a dise axis formed therein; a series o1 vdiscs somounted in said disc chamber thatthereis a narrow slot or openingbetween adjacent discs, each disc being concentric about said disc axis;a bottom cover closing said bottom casing opening; an operating shaftsecured to the upper portion of said valve body and projecting throughthe'top of said casing; and means outside said casing by which saidshaft may be turned and bywhich said valve body may be forced downwardlysol that its outer surface is in. tight contact with the wails of saidvalve chamber when said valve body is in its closed position.

4. ina name arrester, the combination of: a

' casing having a valve chamber therein which is concentric about anaxis, said casing having side casing `openings through which gas canpass through said chamber in a direction substantially at right anglesto said axis, and a bottom casing opening; a valve' body itting in saidvaive chamber androtatable about asid axis andhaving an arrester chamberformed therein which has an inner wall concentric about said axis, saidbody having side valve openings that register with theside casingopenings when the valve body is in open' posi-tion, said side openingsin said casing being closed, or blocked, by the walls of -said valvebody when said valve body is in its closed position, said valvebodyhaving a'bottom valve body opening; an arrester shell adapted toiili and turn freely in said valve'body and having side openingscoinciding with the side openings in said valve body, .sa-id arrestershell being of such size that it may be readily withdrawn through saidboi-,tornl casing opening, and having a disc chamber concentric abouta'disc axis formed therein, said arrester shell having a'bottorn; aremovable cover for the top of said arrester shell; a series of discs somounted in said disc chamber' that there is a narrow slot or openingbetween adjacent dis s, each'discv being concentric about said discasis; abolt secured lin the bottom of said a rester shell and projectingupwardly along the axis of said shell through openings in the centers ofsaid discs; a bolt secured in the cover of said arrester shell andprojecting downwardlyalong the 0i said. shell through openings in thecenters of said discs; a nuton the inner end of each bolt; a sleevesurrounding said bolts having a cavity in; which said bolts canslide'axially; means in which said bolts canfslid-e axially closing theends ofsaid cavity so that the nuts on said bolts cannot be withdrawn.from said cavity: afbottom cover closing: saidbottom casing:opening;'anzd'means out` 7 side the valve casing by which the valve bodycan be rotated.

5. In a flame arrester, the combination of: a casing having a valvechamber therein which is concentric about an axis, said casing havingside casing openings through which gas can pass through said chamber ina direction substantially at right angles to said axis, and a bottomcasing opening; a valve body tting in said valve chamber and rotatableabout said axis and having an arrester chamber formed therein which hasan inner wall concentric about said axis, said body having side valveopenings that register with the side casing openings when the valve bodyis in open position, said side openings in said casing being closed, orblocked, by the walls of said valve body when said valve body is in itsclosed position, said valve body having a bottom valve body opening; anarrester shell adapted to Iill and turn freely in said valve body andhaving side openings coinciding with the side openings in said valvebody, said arrest-er shell being of such size that it may be readilywithdrawn through said bottom casing opening, and having a disc chamberconcentric about a disc axis formed therein, said arrester shell havinga bottom; a removable cover for the top of said arrester shell; a seriesof discs so mounted in said disc chamber lthat there is a narrow slot orOpening between adjacent discs, each disc being concentric about saiddisc axis; a bolt secured in the bottom of said arrester shell andprojecting upwardly along the axis of said shell through openings in thecenters of said discs; a bolt secured in .the cover of said arrestershell and projecting downwardly along the axis of said shell throughopenings in the centers of said discs; a nut on the inner end of veachbolt; a sleeve surrounding said bolts having a cavity in which saidbolts can slide axially; means in which said bolts can slide axiallyclosing the ends of said cavity so that the nuts on saidbolts cannot bewithdrawn from said cavity; a bottom cover closing said bottom casingopening; an operating shaft secured to the upper portion of said valvebody and projecting? through the top of said casing; and means outsidesaid casing by which said shaft may be turned.

6. In a flame arrester, the combination of: a

casing having a valve chamber therein which is' conical about an axis,said casing having side casing openings through which gas can passthrough said chamber in a direction substantially at right angles tosaid axis, and a bottom casing opening; a valve body tting in said valvechamber and rotatable about said axis and having an arrester chamberformed therein which has an inner Wall concentric about said axis, saidbody having side valve openings that register with the side casingopenings when the valve body is in open position, said side openings insaid casing being closed, or blocked, by .the walls of said valve bodywhen said valve body is in its closed position, said valve body having abottom valve body opening; an arrester shell adapted to ll and turnfreely in said valve body and having side openings coinciding with theside openings in said valve body, said arrester shell being of such sizethat it may be readily withdrawn through said bottom casing opening, andhaving a disc chamber concentric about a vdisc axis formed therein, saidarrester shell having a bottom; a removable cover for the top of saidarrester shell; a series of discs so mounted in said disc chamber thatthere is a nar- IOW slot or opening between adjacent discs, each discbeing concentric about said disc axis a bolt secured in the bottom ofsaid arrester shell and projecting -upwardly along the axis of saidshell through openings in the centers of said discs; a bolt secured inthe cover of said arrester shell and projecting downwardly along theaxis of said shell through openings in the centers of said discs; a nuton the inner end of each bolt; a sleeve surrounding said bolts having acavity in which said bolts can slide axially; means in which said boltscan slide axially closing the ends of said cavity so .that the nuts onsaid bolts cannot be withdrawn from said cavity; a bottom cover closingsaid bottom casing opening; an operating shaft secured to the upperportion of said valve body and projecting through the top of saidcasing; and means outside said casing by which said shaft may be turnedand by which said valve body may be forced downwardly so that its outersurface is in tight contact with the walls of said valve chamber whensaid valve body is in its closed position.

7. In a flame arrester, the'combination of: a casing having a valvechamber therein, said casing having a casing inlet opening through whichgases can enter said valve chamber, and a casing outlet opening throughwhich gases may leave said chamber; a primary cover closing an openingin the .top of said chamber; a secondary cover closing an opening in thebottom of said chamber; a valve body rotatable in gas-tight relationshipwith and in said valve chamber, said valve body having an arresterchamber formed therein, said valve body having an inlet valve bodyopening, in the Wall thereof, through which gas may pass into saidarrester chamber and an outlet valve body opening in the wall thereofthrough which gas may pass out of said arrester chamber, said valve bodyopenings being so placed that the inlet valve body opening registerswith said casing inlet opening, and said outlet valve body openingregisters with said casing outlet opening, when said valve body is inits open position, said openings being of such size that the casinginlet and outlet openings are blocked by the valve body when said valvebody is in its closed position, said valve body having an opening in thebottom therey of the full size of said arrester chamber; a pile ofarrester discs in said arrester chamber, said discs being of circularform with their surfaces radial to the axis of the flame arrester, saiddiscs being so separated from each other that gas from said inlet valvebody opening can pass to said outlet valve body opening; and a shaftrigidly connected to said valve body and extending through said primarycover by which said valve body may be turned by force applied theretooutside the flame arrester.

8. In a flame arrester, the combination of: a casing having a valvechamber therein, said casing having a casing inlet opening through whichgases can enter said valve chamber, and a casing outlet opening throughwhich gases may leave said chamber; a primary cover closing an openingin the top of said chamber; a secondary cover closing an opening in thebottom of said chamber; a valve body rotatable in glas-tightrelationship with and in said valve chamber, said valve body having anarrester chamber formed therein, said valve body having an inlet valvebody opening in the wall thereof, through which g-as may pass into saidlarrester chamber and an outlet valve body opening in the wall thereofthrough which gas may pass out of said arrester chamber, said valve bodyopenings being so placed that the inlet valve body opening registerswith said casing inlet opening, and said outlet valve body openingregisters with said casing outlet opening, when said valve body is inits open position, said openings being of such size that the casinginlet and outlet openings are blocked by the valve body when said valvebody is in its closed position, said valve body having an opening in thebottom thereof the lull size of said arrester chamber; a pile ofarrester discs in said arrester chamber,

discs being of circular form with their surfaces radial to the axis o1the ame arrester, said discs being so separated from each other that gasfrom said inlet valve body opening can pass to said outlet valve bodyopening; an arrester shell surrounding said arrester discs and fittingin said arrester chamber in said valve body, said arrester shell beingopen at the top so that the arrester discs can pass freely in and out ofsaid shell, said arrester shell having inlet and outlet openingsregistering with the inlet and outlet openings in said valve body; and ashaft rigidly connected to said valve body and extending through saidprimary cover by which said valve body may be turned by force appliedthereto outside the flame arrester.

9. In a flame arrester, the combination of: a casing having a valvechamber therein, said casing having a casing inlet opening through whichgases can enter said valve chamber, and a casing outlet opening throughwhich gases may leave said chamber; a primary cover closing an openingin the top of said chamber; a secondary cover closing an opening in thebottom of said chamber; a valve body rotatable in gas-tight relationshipwith and in said valve chamber, said valve body having an arresterchamber formed therein, said Valve body having an inlet valve bodyopening in the wall thereof, through which gas m-ay pass into saidarrester chamber and an outlet valve body opening in the wall thereofthrough which gas may pass out of said arrester chamber, said valve bodyopenings being so placed that the inlet valve body opening registerswith said casing inlet opening, and said outlet valve body openingregisters with said casing outlet opening, when said Valve body is inits open position, sai-d openings being of such size that the casinginlet and outlet openings are blocked by the valve body when said valvebody is in its closed position, said valve body having an opening in thebottom thereof the full size of said arrester chamber; a pile ofarrester discs in said arrester chamber, said discs being of circularform with their surfaces radial to the axis of the flame arrester, saiddiscs being so separated from each other that gas from said inlet valvebody opening can pass lto said outlet valve body opening; an arrestershell surrounding -said `arrester discs and tting in said arresterchamber in said valve body, said arrester shell being open at the top sothat Athe arrester discs can pass freely in and out of said shell, saidarrester shell having vinlet and outlet openings regi-stering with theinlet and outlet openings in said valve body, and said arrester shellhaving a bottom upon which said arrester discs rest; a Cover closing theopening in the top of said arrester shell; a bolt projecting downwardlyfrom said cover along the central vertical axis of the arrester insidecentral openings in the arrester discs; a bolt projecting upwardly fromthe bottom of the arrester shell along the central vertical aXis of thearrester inside central openings in the arrester discs; means connectingsaid bolts so that `they may move Within limits coaxially with eachother; and a shaft .rigidly connected to said valve body and extendingthrough said primary cover by which said valve body may be turned byforce applied thereto outside .the flame arrester.

10. An arrester as claimed in claim 7 in which: the valve body has afrusto-conical outer surface having a diameter that increases regularlyfrom the bottom to the top thereof; the inner wall of the casing is so`coned as to t closely on -said valve body; and means are providedoutside the arrester for exerting a downward pressure on the shaftattached to vthe valve body for the purpose of causing the Valve body tot tightly in the casing.

RICHARD =C. HALL.

REFERENCES Cl'IED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 424,305 Jones Mar. 25, 1890691,529 Brophy Jan. 21, 1902 1,363,801 Merrill Dec. 28, 1920 1,646,013Cornell, Jr. Oct. 18, 1927 1,681,698 Brooks Aug. 21, 1928 1,735,261Calhoun Nov. 12, 1929 2,151,180 Anschicks Mar. 21, 1939 FOREIGN PATENTSNumber Country Date 8,870 Great Britain (1904)--Feb. 9, 1905 87,751Sweden Oct. 27, 1936

